Electrode lead



March 19, 1929. I w RUGGLES 1,706,184

ELECTRODE LEAD Filed Aug. 18, 1926 In Vent o1":

Patented Mar. 19, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM A. RUGGLES, F SCHENEOTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRODE LEAD.

Application filed August 18, 1926. Serial No. 130,032.

My present invention relates to electron discharge power tubes and more particularly to electrode leads adapted to carry relatively heavy currents. I

In the ordinary form of power tube the grid lead is usually a small wire extending through a glass seal in the top or side of the tube and adapted to carry currents up to about 20 amperes. The lead is generally welded to the grid sup ort and provided with a few turns inside t e tube in order to facilitate sealing of the tube. With a lead of this type a gas-tight seal is easily made and maintained, and the turns within the tube have. little effect on the operation of the tube owing to the comparatively low frequency currents employed. When the tube is employed in short wave transmission, however, a different situation arises in view of the fact that the grid element may be required to carry a current of the magnitude of one hundred amperes at frequencies varying from ten million to thirty million cycles per second. In order to carry currents of this magnitude the grid lead should be relatively large and it should preferably be straight in order to avoid the inductive effect resulting from the use of turns within the tube. If such a lead is flexible it is not/feasible to make a soldered connection with the grid or to make a gastight seal, while if it is solid, it is impossible to connect the lead directly to the grid, since the expansion of the lead due to the heat developed in the tube is so great that the seal would quickly be broken and the vacuum in the tube destroyed.

It is one of the objects of my invention to provide a flexible connector between a grid and a rigidly mounted lead, which is adapted to carry relatively heavy current without 7 causing injury to the usual glass seal through which the lead extends.

The novel features which' I believe to be characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, will best be understood by reference to the following specification taken vin connection with the accompanying drawing in which Fig. 1 shows in elevation a 20 kw. tube which embodies the features of my invention; Fig. 2 is a perspective view of one form of grid lead comprising a flexible metallic strap de- 5 tachably connected to a grid support and a rigidly mounted lead; while Fig. 3 is a perspective view of a modified form of my invent1on.

Referring to the drawing, I have indicated at 1 a power tube provided with the usual anode 2, cathode and a grid or control. element. .The upper portion of the tube comprises a glass envelope 3 provided with a reentrant portion 4 through which the cathode leads 5 extend and an extension 6 having a reentrant portion including a seal or press 7 into which a solid tungsten lead 8 1s sealed. A metallic grid supporting collar 9, which may be' made of a nickel copper alloy such as Monel or any other suit- 7 able metal, is mounted on the reentrant portion 4 and provided with parallel flanges 10 zvhereby the collar may be secured in posi- The grid lead comprises a flexible strap 11 of annealed copper which extends substantially parallel to the outer surface of collar 9 and is provided with channels 12 at one end thereof adapted to engage the outer surfaces of the flanges l0 and to be detachably secured thereto as clearly indicated on the drawing. The opposite end of the flexible strap 11 is provided with a screw threaded extension 13 adapted to be engaged by a corresponding screw threaded portion 14 on the rigid lead 8.

When the grid or control element of the tube carries a heavy current the amount of heat developed in the tube is very large and as a result strap 11 tends to expand: The expansion of the strap takes place between the .ends thereof and in a radial direction with respect to the collar 9. As a result when the tube is in operation there is no tendency to destroy the vacuum tight seal 95 maintained between the rigid lead 8 and the reentrant portion of the extension 6.

In Fig. 3 a modified form of my invention is shown, which is especially adapted for use with larger currents than the form 100 shown in Figs. 1 and 2. In this case it will be found desirable to employ a heavier strap than that shown in Fig. 2. In such an event strap 11 is merely made longer to provide sufiicient flexibility. This is accom- 105 plished by turning the strap in the opposite direction from that shown in Fig. 2.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. A combined grid lead and clamp for 110 high power discharge devices comprising a metallic sleeve adapted to embrace a portion of an envelop, a metallic strap secured 2. In a large power thermionic apparatus,

a combined grid lead and clamp comprising a cylindrical metallic sleeve adapted to embrace a cylindrical protuberance projecting from the surface of an envelop, a metallic strap detachably secured to the sleeve, said strap comprising a lar e current-carrying cross-sectional area an extending in a direction substantially concentric with respect to the outer circumference of the sleeve and a grid lead adapted flexible conductor ofto be secured to the end of the conductor 20 remote from the stra In witness whereof? I have hereto set my hand this 17th day of August, 1926.

WILLIAM A. RUGGLES. 

